Patted morningglory, Ipomea lacunosa; johnsongrass, Sorghum halapense; and spurge, Euphorbis moculata are among the most troublesome weeds for farmers in the southeastern United States. Full-season competition, especially of johnsongrass and pitted morningglory, can reduce crop yields (such as soybean yields) significantly resulting in serious economic losses in row crop production. One of the most common practices for controlling johnsongrass and pitted morningglory is the use of postemergence selective herbicides. However, there is no single selective herbicide currently available which will give effective control of both weed species.
Substituted imidazolinyl nicotinic and 3-quinolinecarboxylic acids, esters and salts, and their use as herbicidal agents are described in U.S. Pat. Nos. 4,638,068 and 4,647,301 issued to Los and in the counterpart European Patent Specification publication number 0,041,623 A2, published Dec. 16, 1981. These disclosures are primarily concerned with the synthesis of novel substituted imidazolinones and the discovery of the herbicidal activity thereof. The combined use of two or more different imidazolinones is neither suggested nor obvious from these disclosures.
U.S. Pat. No. 4,509,973, issued Apr. 9, 1985, relates to plant growth regulating compositions that contain, as one of the ingredients, a quinolinecarboxylic acid. This patent discloses the treatment of crops with a composition that delivers from 920 to 1610 g/ha of the plant growth regulating agent (2-chloroethyl)trimethylammonium chloride (CCC) as well as about 0.5 to 4 g/ha of 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-3-guinolinecarboxylic acid. Kust et al show that composition is effective for increasing crop yields, but do not teach herbicidal activity.
Wherefore, it is an object of this invention to provide synergistic herbicidal imidazolinone compositions and combination treatments for the selective control of undesirable plant species in the presence of leguminous crops.